so, for kunde_title i put the value of the reseller. whenever i create a new site, its created under the reseller without any problems. But i would like to know how i can add a web to a client instead of a resellers?

for example, i have a reseller called domainseller, and in domainseller, i have a customer called domainclient, so i want to add a site called mydomain.com to customer domainclient. i know i can do this in the ispconfig admin panel, but how can i do it with Remoting Framework?

Webs are never added to a reseller, thats technically impossible. I guess you craeted a customer with the same title and added it to this customer. Just use the title of a existing or newly created customer.